# Physics Colloquium: Luiz Santos, "Emergent Symmetry Protected Topological States"

When |
Mar 23, 2017
from 02:00 PM to 03:00 PM |
---|---|

Where | MR418N |

Contact Name | Myriam Sarachik |

Contact Phone | 212-650-5618 |

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Thursday, March 23: Luiz Santos, University of Illinois at Urbana-Champaign

TITLE: Emergent Symmetry Protected Topological States

ABSTRACT:

Emergence is a central concept in modern condensed matter physics. It accounts for the fact that, due to interactions, the low energy excitations of a quantum many-body system can be drastically different than the bare particles. This concept plays an important role in topological phases of matter, such as fractional quantum Hall states, where low energy quasiparticles behave as fractions of electrons or bosons. In recent years, following the discovery of topological band insulators, it has been noticed that the presence of symmetries can give rise to new classes of topological states, which have been dubbed Symmetry-Protected Topological (SPT) states and are the subject of intense theoretical and experimental studies.

In this talk I will show a novel route to obtain bosonic SPT phases in out-of-equilibrium systems. Specifically I will discuss a scenario where a topologically trivial spin system is periodically

driven with a large frequency, which results in the time evolution of the quantum states being governed by an effective Hamiltonian with emergent SPT properties. In the case of a one dimensional periodically driven Ising chain, the system shows a remarkable decoupling of the dynamics of edge and bulk spins, which implies the presence of non-trivial edge states in this out of equilibrium configuration. I will argue that generalizations of this driving mechanism can be applied in higher dimensions, thus paving the way to create and manipulate SPT states in systems with tunable

coupling constants, such as trapped ions and cold atomic gases.

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The speaker is a candidate for the position of Assistant/Associate Professor of Physics.